Vahid Jamali and colleagues at Stanford are exploring digital communication via chemicals. To be sure, biological organisms signal through chemical channels, including, notably neural communication. And humans have coopted many chemical messaging systems to do our own bidding. (E.g., most drugs work by fiddling with natural chemical communications.)
However, this project is using chemical signals to transmit arbitrary digital bits, which can encode whatever messages we want.
Setting aside the question “why?” for a moment, we note that this is pretty “out there” research. As Professor Andrea Goldsmith comments,
“Every problem that we’ve addressed in traditional wireless communications over the last three or four decades is really different now because it’s a different mode of communicating,” Goldsmith said. “As so, it opens up all of these new ways of thinking about the optimal way to design this type of communication system.”
The researchers have tackled design problems such as selecting chemicals that are cheap, easy to use, and easy to “erase”. They have published papers considering theoretical foundations of this “channel”, and its capacity (such as  and ). (No, I have not worked through these papers in detail-they are quite a bit beyond my own expertise.)
So, what might this be useful for?
They suggest that it might be used for situations where electromagnetic communication is impaired, or even as a backup when power is out. It might also be an unobtrusive way to mark an object or trail for another robot to find, sort of like ants do. This might also be used in nanotechnology and inside bodies, to coordinate swarms of small robots, which are too small and low powered to use radio. Also, chemical channels should be safer for biological hosts than electromagnetic radiation, all else equal.
- N. Farsad, Y. Murin, A. Eckford, and A. Goldsmith. On the capacity of diffusion-based molecular timing channels. In 2016 IEEE International Symposium on Information Theory (ISIT), 2016, 1023-1027.
- Vahid Jamali, Nariman Farsad, Robert Schober, and Andrea Goldsmith, Non-Coherent Multiple-Symbol Detection for Diffusive Molecular Communications, in Proceedings of the 3rd ACM International Conference on Nanoscale Computing and Communication. 2016, ACM: New York, NY, USA. p. 1-7.